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The Marine Aquarium: A Components Breakdown

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The goal of this collection is to give the beginner hobbyist a good idea of what each of the components of the marine aquarium is, and what they do. While not all the components covered in this collection are necessary items, they all do have their function, and can be useful in the right situations. We'll start by dealing with the necessities, and then go to dealing with those that are best practice, and finish with the optional items.

The Tank
This is obviously an essential to the hobby, but what kind of tank you choose will play an important role in your setup. There are many sizes available and even many shapes. Modern technology has allowed us to bend glass and shape it just about anyway your want, and with the option of using acrylic tanks, the shapes and sizes expands even more. So first, lets look at the most popular choice for marine hobbyists; the Reef Ready tank. A tank that is “reef ready” is simply a tank that has had holes drilled in the bottom and overflows installed so that a sump can easily be used. These holes must have bulkheads installed in them to allow the hobbyist to plumb the sump properly. If the hobbyist does not choose to use a sump with this kind of system, bulkhead plugs can be installed instead of pipes and hoses. Generally, however, if you are going to put out the extra money for a drilled tank, you are going to use a sump with it.
Shape is something else to consider. Practically any shape you get will work for a marine aquarium, however there are some that are a little less practical. Hexagon tanks will work, but remember, when you have to start cleaning that beautiful coralline algae, it is going to love all those corners, and it will be a little more difficult to get to. Also, since hexagon tanks are tall rather than wide, they restrict surface area, and thus gas exchange. That added height also means you are going to need a more intense light to reach the lower regions of the tank if you decide to do a reef in it. Again, it can be done, but it is just a bit more difficult. The above points are pretty much the keys for deciding on the shape of the aquarium you want. While they can be nice, odd shapes can be a pain to maintain.
We briefly mentioned acrylic at the beginning of this section, so lets take a closer look at the benefits and drawbacks to this material. One of the biggest benefits to acrylic is that it is much lighter than glass, and is well suited for large aquariums. Most tank owners who purchase a tank that is greater than 240 gallons, purchase an acrylic tank simply because they are lighter, and at that size, they are even more durable. A panel of glass that is 8 feet long and 2 feet high will generally be much weaker in the middle, than a piece of acrylic of the same thickness. While the acrylic will bow easier, it will not break due to the flexibility of the material. The flexibility of acrylic also allows it to be molded into a large variety of shapes without the use of any seams. The seams are another area where acrylic tanks excel. Glass tanks must be bonded together with silicone, and on larger tanks, they have bracing added to the top and bottom to properly support the glass panels so that they do not break. Acrylic tanks have the major advantage of being welded together. Welded seams form a much stronger bond since they chemicals literally melt the acrylic together, thus in essence making all the pieces of acrylic used, one large piece. Bracing will still be required on the top of large acrylic aquariums, but as with the rest of the pieces, the bracing is welded in place creating a very strong bond. Acrylic does have a couple of major drawbacks though, and the biggest of these is price. Acrylic aquariums for some of the more common sizes, are as much as double the prices of their glass counterparts. Acrylic also scratches much easier, so the hobbyist must take care when placing rocks, and cleaning the panels. A piece of sand in your algae brush can make an absolute mess of your expensive acrylic tank.
The final aspect of the tank that we must look at is the choice of size. This is an area of great debate. The size tank you choose will depend on a few factors. The first factor that you must consider is your experience level. If you are just a beginner to the marine hobby, a 10 gallon tank is not likely to be the best option for you as stability of the environment is directly proportional to the size of the tank. The best option for the beginner marine hobbyist, is to get the largest tank you can afford, for the space you have to put it in. This is where we can get back to the shape issue again. If you only have an area that is 2 feet long in which to place your tank, the a taller tank may not be a bad option for you, but remember, you can also add volume to the system by setting up a sump system. Using a continuous siphon overflow is always an option for the use of a sump system if you cannot obtain a drilled tank is the size tank you need. I've already mentioned the other 2 factors, and they pretty much go together. Size and cost are another a pair of factors that must be considered. These usually go together simply because the larger the tank you choose, the higher the cost is going to be for everything. All these factors put together should help you choose the proper tank for you.

The Stand
You would think this a really easy choice, and in some respects it is, but there are still some important factors to be considered. The stand must obviously be the right size for the footprint of the tank you have chosen. Purchasing a stand that is too large can mean that your tank is not properly supported. In improperly supported tank can mean disaster. You also need to be sure to purchase a stand that is going to adequately support the weight of your tank. A marine aquarium is going to be a very heavy setup, and must be supported adequately. Most commercial stand on the market today are going to be sufficient to support your tank. Although some may look rather flimsy, they are surprisingly sturdy. Be sure to check the load bearing capacity of the stand you purchase since not all stand that will fit the footprint of your tank will be designed to hold the volume of your tank. For example, there are stands available on the market that are rated for 20-29 gallon aquariums, and have the same footprint as a 37 gallon tank. While these stand may well hold your aquarium, it is best that you choose one rated for a 37. When you consider the weight of the aquarium, you mast factor in the weight of the tank, rocks, sand, and water together, not just the tank and water. A good rough estimate for weight is roughly 10 pounds for every gallon of volume, so the estimate for a 75 gallon aquarium would be roughly 750 pounds.
The final consideration when choosing a stand is weather or not you will be employing the use of a sump or not. There are many stands available on the market that will be completely inappropriate for setting up a sump. If you plan to use a sump, be sure the stand you choose is able to support it's use. When choosing your stand, it is probably best that you choose one that will be able to support the use of a sump even if you are not planning on a sump. By choosing a stand such as this, it gives you the freedom to add a sump at a later date if you so choose.
The rest of the considerations for a stand are going to be purely aesthetic in nature, and are probably best left to the one in charge of decorating the interior of your home. Of course, if you are unable to find a stand that suits you, or if you want to do something a little more cost effective, there are plenty of plans available on the internet for building your own stand. Just be sure to follow all the same considerations when building rater than buying.

Heater
This is an area that does not really require much discussion. It is a generally accepted standard that the hobbyist chose a heater that has a wattage of between 3and 5 times the volume of the tank. Very simply and the choisc of heater is up to the hobbyist.

Lighting
This will probably be the most lengthy section of this entire series as it is probably the most complex. There is no easy answer to the lighting question so we will simply deal with each kind of light available to the hobbyist. Your choice of lighting type will depend on the kind of aquarium you plan to keep, and the kinds of corals you wish to keep in a reef environment.
Normal output fluorescent lights are still a viable option for a marine aquarium providing you are not planning to keep any photosynthetic organisms. Normal output fluorescent lights are generally the T12 bulbs found at your local home improvement store. While T8 bulbs are slightly more intense than the T12s, they do not require special ballasts to run and thus we will include them in this section.
The next step up on the intensity list will be the VHO fluorescent lights. These are generally a T12 bulb as well however they are driven by higher powered ballasts. VHO lighting is extremely uncommon these days as it is largely considered to be a old, inefficient technology. The new hobbyist is unlikely to encounter this kind of lighting, and even far less likely to employ it. However, if the new hobbyist decides to use these (ie. they get them with a used tank) these can support a wide range of corals. With these lights, the length and number of bulbs is going to determine the power and number of ballasts needed to run them. With enough of these bulbs employed, many soft corals can be kept as well as a few LPS corals. With enough of these bulbs employed, the hobbyist can even maintain certain anemones. However, to get enough light on your tank from these lights to keep organisms like anemones, you will need a number of them. For the power you will use to run these lights, you can get far more light with other options.
Next on the intensity scale is the Power Compact fluorescent light. These are also going to be good for keeping a wide variety of corals. The intensity of power compact bulbs is higher than that of the VHOs but is still highly inefficient. Power compact lighting will be sufficient for many soft corals, a few LPS corals, and only one or two species of SPS coral. Even though corals such as Monti caps can be supported under power compact lighting, they will need to be placed high in the tank very close to the lights.
T5 High Output lights are next on the agenda. These lights have a far greater output than power compacts, and due to their small diameter, it is possible to fit more of them in a smaller area. T5s are also highly efficient in their output to watts used ratio. T5 lights are suitable for all but the most light demanding of corals, but with a sufficient number of bulbs, even these can be kept. The wonderful thing about T5 bulbs is that over the life of the bulb, it will only lose 5% of it's intensity, and they generally do not experience the drastic spectrum shift associated with power compacts or metal halides.
We finally reach the pinnacle of intensity with the might metal halides. Metal halide bulbs are the tried and true workhorse lights of the marine hobby. These lights have been in use in the hobby for at least 3 decades. They are slightly more versatile than the fluorescent bulbs in that their output is not restricted to a given length of bulb. With a single bulb you can place 75, 150, 175, 250, 400, or even 1000 watts of power above your tank. This may not seem that important, but when you are dealing with that tanks that have a small footprint, but are still quite tall, it makes lighting even the deepest parts of the tank a simple task. With a sufficiently powerful ballast and bulb combination, you can grow even the most light demanding of organisms in the hobby.
For each of these kinds of lights, the hobbyist is also presented with a wide variety of choices in color temperature with is expressed in degrees Kelvin (K). The fluorescent bulbs are the only ones that have the actinic bulbs available, metal halides do not, in fact, Metal halides have the fewest choices available to the hobbyist with just 4 choices in color temperature. The choices for the metal halide bulbs is limited to 6700, 10k, 14k, and 20k. The 6500K bulbs are not a popular choice for the marine hobbyist since they create more of a yellow look in the water rather than the desirable blue. The fluorescent bulbs come in varieties of 6700K, 10k, 12k, 14k, 18k, and 20k, and the normal output T12 lights have even more choices than that. Again, anything under a 10k bulb is not likely to be a great choice for the marine hobbyist as it gets further from the desired blue color. Also, the fluorescent bulbs come in two different spectrum ranges for actinic bulbs, and even a full spectrum bulb that ranges from 360-720nm wave lengths.
I've left the discussion of LED lighting til this point on purpose. The reason I've left them til now is that the issues discussed iun previous paragraphs all change when you get to LEDs. Intensity and color temperature are both variable with the LEDs and there no need to talk about replacement bulbs as they do not burn out like traditional light sources. With the LED fixtures, you can increase the amount of light simply by increasing the number of bulbs you have on, and with most models out there, the overall color temperature can be varied through a control panel. LEDs currently face on major drawback, and that is price. Even with the cost of operation and replacement bulbs factored in, T5, power compact, and even some metal halide fixtures come in at a lower cost. For a decent set of LEDs for a standard 55 gallon reef tank, the hobbyist is still looking at over $1000 up front, and cost of operation is not completely eliminated. When compared with the average T5 fixture, the LED fixtures do not offset the cost of the T5 fixture for 5-10 years. This is something that the average hobbyist is going to be unwilling to pay. Also, LED fixtures are still a relatively new technology in the aquarium hobby, and as such they are still in the first and second generations in many cases. This keeps the price up, and it also means they are still working the bugs out of them.
Lighting for the reef aquarium is as variable as filtration for the freshwater tank. There is not a single right answer on how to do things, and the requirements will vary from tank to tank. Coral species is merely one factor to consider when purchasing lighting. Probably a factor of equal value will be the height of the tank. For some tanks, depending on species of corals chosen, nothing but metal halide lighting will be sufficient. Tanks that are up around 30 inches in height are going to need a light that can penetrate to the bottom of the tank, and still provide sufficient PAR for coral growth. In most cases, that light will have to be a metal halide of some strength. For those wishing to keep more light demanding organisms such as Tridacnid clams on the substrate, you will be looking at either 250 or 400 watt metal halides.
So, in summery, factor in the height of your tank, consider the coral species you wish to keep, and then figure out your budget for lighting and make your choice.

Power Heads
Just as important to the health of many corals as light, is water movement within the tank. This is something that is vitally important to your marine aquarium, especially if you are using live rock as your filtration. Without water movement, you have no filtration. We express the flow in a tank in terms of gallons per hour (GPH) and then take that to calculate the number of times the entire volume of the tank is “turned over” by that flow. The normal recommended base for flow is a 10 times per hour turnover rate of the tank. That base will change based on the species of coral chosen though. In a FOWLR tank the base of 10 times will likely be sufficient, and it must be directed properly to avoid dead spots within the aquarium. Generally flow is achieved through 3 different methods: protein skimmer, external pump, and powerheads. The external pumps are usually in a sump, but some chose to employ a closed loop system with an external pump, however these are mostly employed on larger systems.
For our purposes we will stick to the discussion of powerheads, as these are the main source of flow in any marine aquarium. There are basically 2 kinds of powerhead available to the hobbyist; impeller driven, and propeller driven. When one thinks of an impeller driven powerhead, one most often things of the Aquaclear and Maxi-Jet powerheads. These powerheads deliver a strong concentrated jet of water that can be easily directed by adjusting the output nozzle. These powerheads rely on high pressure with relatively low volume. On the other hand we have the propeller driven powerheads such as Koralia, Tunze, and Vortec. All of these powerheads use a propeller to push large amounts of water at a lower pressure. The effect of these power heads is a flow that much more closely resembles nature. The other advantage these powerheads have is they do not transfer as much heat to the aquarium since they do not require as much power to run the motors. The Vortec powerheads are even in a class of their own in this category because the motor assembly is on the outside of the aquarium, and the propeller is the only part inside the aquarium. The propeller of the Vortec powerheads is driven by magnets in the motor assmebly. This provides a huge advantage in the area of heat transfer, and there is virtually no heat transferred to the tank.

Protein Skimmer
With the introduction of the protein skimmer, we have moved from the necessary equipment into the category of best practice equipment. I'm sure that statement will raise a few eyebrows among some hobbyists as there are many that consider it a vital piece of equipment. They are entitled to that opinion, but there are certain cases where a protein skimmer can in fact be a detriment to a healthy marine environment. The function of the skimmer is to remove organic compounds from the water to aid the filtration in the removal of nitrogenous waste. While it is a physical process, it is a also a chemical process at the same time. Each organic compound has has a charge, and that charge allows them to attach to the bubbles in the skimmer. These bubbles rise in the the column of the skimmer and as they break at the top of the neck, the attacked compounds are deposited in the collection cup. Obviously the process is more complicated than that, and not all compounds are attracted to the air bubbles and thus there are certain things that a skimmer does not remove.
Protein skimmers have come a long way since the early days when they were driven by an air stone. Today there are 3 main kinds of skimmer on the market, and they all vary in efficiency. First came the Berlin style skimmer. These skimmers rely on a powerhead pushing water into a cylindrical chamber creating a vortex, at the same time, an air line is positioned between the cylinder and the powerhead causing air to be drawn into the water stream creating the necessary tiny bubbles. The amount of air drawn in is generally controlled by a small valve at the end of that air line, or by a set screw. Either way, the hobbyist controls the amount of air being injected into the skimmer Next we have the needle wheel skimmers. These skimmers do not require the cylindrical shape of the Berlin skimmers, although they often do maintain that same shape. Again, air is still require in the use of these skimmers, however unlike the Berlin skimmers, the air is not injected after the powerhead, but rather the air is drawn directly into the skimmer pump itself. In an impeller driven pump this would eventually lead to the problem of cavitation, which will destroy an impeller, however due to the slender spines of the needle wheel, the air that is drawn in, is broken in extremely tiny bubbles. This makes these skimmers far more efficient that the Berlin style skimmers. With a needle wheel skimmer, the amount of air being drawn in through the air line is typically larger than with a Berlin skimmer, and it is usually not adjustable. Instead, many needle wheel skimmers have an adjustable collection cup height. Finally we have the recirculating skimmers. These are considered to be the most highly efficient skimmers available to the hobbyist. Recirculating skimmers are fed by gravity from the overflow of the aquarium, and the pumps are used to recirculate the water in them many times over. The theory as that the longer the water is in the skimming process, the more it will pull out. Typically the motors in these skimmers are needle wheel pumps, however the same water goes through the pump multiple times before being returned to the tank. There are a couple other kinds of skimmers that are produced, but neither is very popular in the hobby, and not likely to be encountered by today's hobbyist.

Sump
This is another optional piece of equipment for the hobbyist. The 3 main functions of a sump are as follows: increased water volume, hiding equipment, and providing a place for physical filtration. The hiding of equipment is merely an aesthetic function of the sump. Many hobbyists do not like to see a heater hanging in the tank or a protein skimmer hanging off the back, and they would much rather place them in the sump. This function is the primary function of a “sump” in the all-in-one nano systems being marketed today.
Increased water volume though is more than a function of aesthetics, it plays a role in the stability of the system. The higher the water volume, the less concentrated the organic compounds will be, and thus the easier it is too keep those concentrations low. Oddly enough, this particular reason for a sump is where we get the most contradiction between theory and reality. In theory, the smaller the volume of the main aquarium, the larger the volume of the sump should be, however this rarely plays out in reality. In fact, many people recommend that a sump be a set percentage of the size of the main tank. This simply means that the size of the sump will increase proportionally to the size of the aquarium. When considering this factor in the use of a sump, it is important to remember, that all marine systems are inherently unstable environments due to their limited size, and the use of a sump only serves to increase stability, it never makes it completely stable. A 75 gallon marine tank with no sump will be every bit as stable as a 55 gallon aquarium with a 20 gallon sump, the difference in water volume is minimal. As for physical filtration, this sort of falls under the aesthetic issue as many do not want to employ either a canister or hang on back model filter because they add equipment to the tank. The other isse here though is easy of maintenance. There can be no doubt, that cleaning a filter sock in a sump is far easier than reaching over your tank to remove a cartridge from a power filter, or opening a canister to clean it.

Reactors
This is a multifaceted category much like lighting, but it is a category of entirely optional equipment. There is not a single reactor out there that is a necessity for any marine aquarium. For the purposes of this article, we will deal with the 3 main kind that are available, and are most commonly used.
First we have the calcium reactor. These reactors are mostly employed on larger systems that are dedicated to nothing but stony corals, where the demand for calcium is very high. Because stony corals, and clams all need large amounts of calcium to grow, it needs to be provided in sufficient amounts. While this can be accomplished through a couple of methods, for the high demand systems, the calcium reactor is the method of choice. A calcium reactor works by dissolving the media (calcium carbonate chips) into the water flowing through it. This isn't quite so easy though, as calcium carbonate does not naturally dissolve in salt water due to it's high pH. Only when the pH of the water drops below 7.8 will this compound dissolve. To achieve this safely within a marine environment, CO2 is injected into the water being pushed through the reactor thus lowering the pH to a level where the media will dissolve. As the water leaves the reactor, it carries it's new deposit of calcium with it to the tank for use.
Next is the phosphate reactor. This reactor is merely a chamber where media is used to remove phosphate from the water. There is nothing special injected into the water, just a special media that will remove phosphate. Again, these are largely used on systems with large numbers of stony corals due to the fact that phosphate will limit the growth of stony corals.
Finally we have the newest of the reactors, the carbon reactor. No, this is not a reactor for using activated carbon, but rather a reactor where carbon is dissolved into the water. This is a function of water purification. The theory behind it is that the added carbon will allow the bacteria to work more efficiently to remove nitrogenous waste thus keeping the water super pure allowing for maximum growth and health of the invertebrates in the system.

There are other pieces of equipment out there available to the hobbyist, but many are simply toys for the high tech hobbyist to use. I have intentionally left out the UV sterilizer simply because it is my personal opinion that they do not belong on a display system, but should be limited to use in a quarantine system or only in emergency cases on the display tank. Just to make you aware of some of the other things out there here is a list of other equipment that some will employ.

Water parameter probes (salinity, pH, and dissolved oxygen are the most popular)
Ozoneizer (not very common anymore, and can have disastrous results if not employed properly)
Dosing pumps (for automatic dosing of chemicals)

Hydrometers and RefractometersThese really are an indispensable piece of equipment for the marine hobbyist, unless you are buying premixed saltwater from your local fish store. Many make the mistake of stating that they measure the salinity of your water, when in fact they do not. Both of these instruments measure the Specific Gravity (aka Relative Density) of your water.

First the Hydrometer. Hydrometers have mostly fallen out of favor among most hobbyists because they are decried as being inaccurate. This is true, but only for the swing arm style hydrometers. A standard hydrometer that is calibrated for measuring the specific gravity of salt water is actually a highly precise piece of scientific equipment. A standard hydrometer is simply a hollow floating instrument made of glass that is weighted at one end, and looks somewhat akin to a thermometer. The weight and the units of measurement are calibrated specifically to salt water at a give temperature. These can be a bit difficult to find for the hobby, and have unfortunately been lumped together with their swing arm style cousins in being labeled inaccurate. As you probably have learned in your elementary science classes, as you add dissolved solids to water, you increase the density of the water. The hydrometers will float at different levels depending on the relative density of that given sample. All hobby hydrometers are calibrated to water with 0 total dissolved solids.

Second we have the Refractometer. As the name indicates, a refractometer measures the refraction of light through a given liquid. As the density of the liquid changes so does the angle of refraction. The denser the liquid, the more the angle is changed. A refractometer measures this angle and gives the relative density of the sample of water. However, something that people often forget, is that they must also be calibrated. This is accomplished by placing a sample of Reverse Osmosis / De-Ionized water on the refractometer. If your refractometer is properly calibrated, it will read 1.000. Some refractometer models have the ability to be adjusted by the use of a small set screw on the top of the unit. Not all units are adjustable. Don't be fooled into thinking that a $200 refractometer is better than a $45 model. Both will adequately do the job you need them to do, so there is no need to break the bank for the more expensive model.

If there are other pieces of equipment that you would like to see discussed, please post them and I will endeavor to explain them.

Great write-up for people who are thinking about getting into the salt water side of the hobby. The part on lighting is really good

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If you take your time to do the research FIRST, you can successfully set-up and keep ANY type of aquarium with ease."Not using a quarantine tank is like playing Russian roulette. Nobody wins the game, some people just get to play longer than others." - Anthony CalfoFishless CycleCycling with FishMarine Aquarium Info [URL="http://saltwater.aquaticcommunity.com/"]